Humidity climbs so high in certain areas of the country that mildew can be a problem. During the muggy months it can develop in damp cellars and basements, poorly aired closets, dark crawl spaces and nonventilated bathrooms.

The result? A musty odor, discolored walls or rotted materials. Cotton, linen, rayon, silk, wool, leather, wood and paper are the most susceptible materials.

To prevent the spread of mildew or to remedy it in moist environs, one must waterproof, ventilate and properly clean these areas, according to the Soap and Detergent Association. Here are some tips from its experts:

To control the cause of dampness, replace cracked or defective mortar around a house. Check that drainage is adequate. Consider waterproofing concrete and other masonry walls above ground. Seal absorbent brick and other surfaces. Prevent moisture from entering crawl spaces by spreading a layer of moisture-barrier material over the soil under the building.

If natural breezes are not sufficient, create good ventilation. Use an electric fan to circulate air. Air-conditioners take up warm air, cool it and circulate the cool air back into a room. A dehumidifier controls humidity.

Keep closets, dresser drawers, basement, bathrooms and other susceptible areas as clean as possible.

Water-repellent sprays, fungicides and chemicals to absorb moisture help keep fabrics and surfaces free of moisture and mold.

If mildew has appeared on clothing or household fabrics, remove spots as soon as discovered before mold can weaken materials. Begin by brushing off mold outdoors so mildew spores do not scatter in the house. On washable fabrics, pretreat by rubbing detergent into the dampened strain. Then launder the items in hot water and chlorine bleach, if safe for fabric, and detergent or soap.

If stain remains, sponge with hydrogen peroxide. Rinse and launder. If you can't use bleach, soak items in oxygen bleach. Then wash. Nonwashable items should be dry-cleaned.

If mildew is on upholstered pieces, mattresses, rugs or carpets, start by taking the mildewed item outside and brush mold away with a broom. Using the upholstery attachment of a vacuum cleaner, run it over the surface to draw out more mold. Since mold spores are going into the vacuum, dispose of bag outside.

Sun and air items thoroughly to stop mold growth. If mildew remains on upholstered furniture, wipe it with a cloth wrung out of a dilute alcohol solution; (one cup denatured or rubbing alcohol to one cup water). Dry the article thoroughly. Sponge mildewed rugs and carpets with a rug shampoo or use an electric shampoo machine. If possible, let the item dry in the sun.